Web searching has become a common technique for finding information. Popular search engines allow users to perform broad based web searches according to search terms entered by the users in user interfaces provided by the search engines (e.g. search engine web pages displayed at client devices). A broad based search can return results that may include information from a wide variety of domains (where a domain refers to a particular category of information).
In some cases, users may wish to search for information that is specific to a particular domain. For example, a user may seek to perform a job search or to perform a product search. Such searches (referred to as “query intent searches”) are examples of searches where a user has a specific query intent for information from a specific domain in mind when performing the search (e.g. search for a particular type of job, search for a particular product, and so forth). Query intent searching can be provided by a vertical search service, which can be a service offered by a general-purpose search engine, or alternatively, by a vertical search engine. A vertical search service provides search results from a particular domain, and typically does not return search results from domains un-related to the particular domain.
A query intent classifier can be used to determine whether or not a query received by a search engine should trigger a vertical search service. For example, a job intent classifier is able to determine whether or not a received query is related to a job search. If the received query is classified as relating to a job search, then the corresponding vertical search service can be invoked to identify search results in the job search domain (which can include websites relating to job searching, for example). In one specific example, a job intent classifier may classify a query containing the search phase “trucking jobs” as being positive as a job intent search, which would therefore trigger a vertical search for information relating to jobs in the trucking industry. On the other hand, the job intent classifier will classify a query containing the search phrase “bob jobs” (which is a name of a person) as being negative for a job intent search, and therefore, would not trigger a vertical search service. Because “bob jobs” is the name of a person, the presence of “jobs” in the search phrase should not trigger a job-related query intent search.
A challenge faced by developers of query intent classifiers is that typical training techniques (for training the query intent classifiers) have to be provided with an adequate amount of labeled training data (training data that has been labeled as either positive or negative for a query intent) for proper training of the query intent classifiers. Building a classifier with insufficient labeled training data can lead to an inaccurate classifier.